1. Field of the Invention
This invention relates to the filtering of a fluid and more particularly to a fluid filter and method of making incorporating a sintered bonding material for securing filter media.
2. Background of the Invention
Various apparatuses and methods have been utilized by the prior art for removing suspended contaminants from a contaminated fluid. In general, the contaminated fluid is passed through a porous filtering media by an external pressure or an external force. The pore size of the porous filtering media is selected to permit the passage of the fluid therethrough while inhibiting the flow of contaminants through the porous filtering media. The contaminants are blocked by the porous filter media while the fluid passes through the porous filter media. The fluid flowing through the filter media is purged of the contaminants.
After a period of time, the contaminants collected by the filter media overlay the pores of the porous filter media thereby blocking the pores and reducing the passage of the fluid therethrough. The blockage of the pores of the filter media by the collected contaminants reduce the flow rate of the fluid through the fluid filter thereby rendering the fluid filter unsuitable for continued used. In many cases, the fluid filter was discarded and replaced with a new fluid filter to reestablish the desired flow rate of the fluid in the fluid filtering process.
In a typical fluid filter, a porous filter media is secured to a filter support or the like for mounting or suspending the filter media. In the case of a cylindrical filter, the filter media is formed into a cylindrical configuration and a first and a second cylindrical end of the filter media are bonded to a first and a second filter support such as a first and a second end cap. The first and second end caps mount the filter media relative to a fluid input source and a fluid output source. In many cases, a braze material is used for affixing the first and second cylindrical ends of the filter media to the first and second end caps.
In one example of the construction of the fluid filter, the first end cap was placed on the horizontal surface facing upwardly and filled with a braze material. The first end of the filter material was inserted into the braze material contained within the first end cap and the assembly was heated for melting the braze material to bond the first end of the cylindrical filter media to the first end cap. A second end cap was placed on a horizontal surface facing upwardly and was filled with a braze material. The second end of the filter material was inserted within the braze material contained within the second end cap and the assembly was heated for melting the braze material to bond the second end of the cylindrical filter media to the first end cap. A distinct disadvantage of the aforementioned process was that the bonding of both the first and second cylindrical ends of the filter media required two separate and distinct heating processes.
Some in the prior art have used a combination of a powdered first braze material having a first melting point, a powdered second braze material having a second melting point, and a binder material for controlling the position and migration of the powdered braze material during the heating process. The use of the binder material enabled the powdered braze materials to be positioned within an inverted end cap to allow both the first and the second ends of the cylindrical filter media to be bonded to the first and second end caps during a single heating process. The binder material prevented the powder braze materials from being discharged from the inverted end cap. In addition, the binder material inhibited the migration or wicking of the braze material into the filter media during the heating process. The binder material was burnt away leaving only the braze material to bond the first and second ends of the cylindrical filter media to the first and second end caps.
U.S. Pat. No. 2,642,187 to Bell discloses a replaceable filter unit of the character described comprising a pleated filter body of resin-impregnated paper arranged in tubular form and with the pleats extending substantially radially, end discs of the same material as the filter body closing off opposite ends of the body, said discs being bonded by a thermosetting resin adhesive to opposite end edges of said pleats, said adhesive lying between under faces of said discs and corresponding end edges of said pleats in contact therewith, and having turned down rims bonded adhesively by thermosetting resin adhesive to folds of the pleats, said adhesive lying between inner faces of the turned down rims and the folds of the pleats in contact therewith.
U.S. Pat. No. 2,877,903 to Veres discloses a unit for filtering particulate matter from a fluid flowing therethrough, a hollow filter body comprising a screen equipped with a screen closure at one end thereof, a cap substantially closing the other end of said screen body and defining connecting means for communicating the interior of said filter body with a fluid flow line, and a mass of pellets defining a substantially continuous coating along the outer surface of the screen end closure and screen body and being bonded to each other and to the screen body and end closure to form an integrated structure therewith, whereby both said screen body and screen end closure define filtering areas through which fluid may pass to the interior of the screen body.
U.S. Pat. No. 2,957,235 to Steinberg discloses a method of assembling first and second elements composed of a mixture of powdered metal and resinous binder comprising placing said first element on a support, heating said first element until said resin binder therein becomes pliable without the element losing shape, placing said second element against said first element, applying pressure to said second element until a bond is formed by the resinous binder between said first and second elements, removing the elements from said support, cooling the assembly of said elements, supporting said assembly with sinter material in a sintering zone, and sintering said assembly into a unitary sintered structure.
U.S. Pat. No. 3,490,902 to Fisher discloses a method for forming porous structures useful, for example, as filters, diffusion membranes, sound absorbers, and the like. The structures contain a sintered metal portion at least one surface of which having embedded and bonded thereto a reinforcing member. Some of the fibers in the fiber metal portion are bonded to each other and to the reinforcing member.
U.S. Pat. No. 3,716,347 to Bergstrom et al. discloses metal parts joined together with sintered powdered metal by applying a mixture of powdered metal and an organic heat-fugitive binder to the parts at the locus of the joint to be formed therebetween, assembling the parts in their desired joined configuration, and heating the assembly to volatilize or burn-off the binder and sinter the powdered metal.
U.S. Pat. No. 4,114,794 to Storms discloses an autogenous or sinter bond between metallic filter media and other metal components of a filter assembly is produced by joining the parts through a diffusion bonding membrane. The membrane comprises a web of small diameter metal fibrils which will sinter bond to both the filter media and the other filter parts to form a physically strong and leak-free seal.
U.S. Pat. No. 4,169,059 to Storms discloses an autogenous or sinter bond between metallic filter media and other metal components of a filter assembly is produced by joining the parts through a diffusion bonding membrane. The membrane comprises a web of small diameter metal fibrils which will sinter bond to both the filter media and the other filter parts to form a physically strong and leak-free seal.
U.S. Pat. No. 4,290,889 to Erickson discloses a new and unique means for preventing the crowns of a backflushable filter element unit from splitting which has heretofore been caused by the cyclic action of the cleaning and backflushing. A layer of staple material is positioned adjacent the outer layer of filter media to prevent bellowing or ballooning. An additional staple layer may be positioned adjacent the inner layer of filtered media to provide additional support. With both staple layers in position on both sides of the filter media, the media is firmly captured and the crowns will not split.
U.S. Pat. No. 4,676,843 to Nazmy discloses two component workpieces consisting of different superalloys or of the same superalloy are bonded together to form a monolithic whole, with the insertion of a layer 1-2 mm thick consisting of a powder of composition similar to or identical to that of the component workpieces, by hot pressing in accordance with the diffusion bonding process. The workpiece surfaces to be bonded do not have to have narrow tolerances, but are with advantage provided with grooves.
U.S. Pat. No. 4,875,616 to Nixdorf discloses a method for producing a high temperature, high strength bond between a ceramic shape and a metal substrate, such as joining a ceramic cap to a piston for an internal combustion engine. The composite joint is effected through the use of a ceramic preform fabricated using fibers, whiskers, platelets or sponge-like particles having the same composition as the ceramic body. The preform is joined to the ceramic shape by using a ceramic slip having a ceramic corresponding in composition with the ceramic body, with this juncture being heated to achieve a secure bond. The preform is joined to the metal substrate by first infiltrating the preform with molten material corresponding to the substrate, and then pressure bonding the infiltrated preform to the substrate after the molten material has solidified. The substrate can be metal or metal alloy. An example is given for the bonding of silicon carbide to a 300 series aluminum.
U.S. Pat. No. 5,230,760 to Tanabe discloses a filter cartridge of micro filtration membrane pleats type, by which it is possible to stably manufacture products of high quality and to reduce the manufacturing cost. In the method for manufacturing a filter cartridge of micro membrane pleats according to the present invention, an initial portion and a last portion with pleats of a micro filtration membrane are welded together to prepare an endless micro membrane, and a filter element provided with a micro filtration membrane is welded on two end plates. A thin bonding auxiliary plate made of the same material as the end plates, having an opening at its center and molten at relatively low temperature, is welded to filter element and end plates which are heated in advance.
U.S. Pat. No. 5,350,515 to Stark et. al. discloses a filter cartridge including a cylindrical filter medium potted into a top cap, and having an internally potted bottom closure molded in place inside the filter medium.
U.S. Pat. No. 5,395,039 to Koehler et. al. discloses such a braze material and process. The same braze material and process is disclosed by a prior NICROBRAZ Technical Bulletin of 1991 published by the Wall Colmony Corporation regarding a braze material sold under the trademark "NICROBRAZ".
U.S. Pat. No. 5,545,323 to Koehler et al. discloses a filter assembly and a method of making a filter assembly described wherein a filter pack is seated in an end cap and contacted with a particulate material and a settling liquid of low viscosity to form a filter assemblage. The filter assemblage is sintered to form a strong, virtually impermeable bond therebetween.
Another disadvantage of the aforementioned brazing process is the introduction of foreign braze materials into the filter assembly. In many cases, the filter media and the filter support are made of the same type of material which is selected to be impervious to the fluids flowing through the filter media. The brazing process introduced braze materials that are dissimilar to the type of material of filter media and end caps. Accordingly, the compatibility of the type of braze material must be considered for use with the fluid to be filtered by the filter media.
Others in the prior art have devised devices and methods for cleaning the fluid filter to remove the contaminants collected by the filter media. Typically, the process of removing the contaminants from the filter media involved the flow of a solvent material such as acids, bases and organics or the like through the filter media in a direction opposite to the direction of the fluid through the fluid filter. In some cases, the solvent material was passed through the filter media when the fluid filter was raised to an elevated temperature.
In many cases, a reusable fluid filter is used for polymer melt, gas and hydraulic filtration. The effective costs of a reusable fluid filter may be decreased by increasing the useful life of the reusable fluid filter. The useful life of the reusable fluid filter is determined by the number of high temperature, corrosive solvent cleaning cycles the reusable fluid filter can be subjected to without deterioration. One of the more important components is the material used to secure the filter media within the fluid filter. This material must be capable of withstanding the same cleaning, processing and manufacturing conditions as the filter media.
Therefore, it is an object of this invention to provide an improved fluid filter assembly and method of making incorporating a filter media which is bonded to a filter support through the use of a sintered fiber material.
Another object of this invention is to provide an improved fluid filter assembly and method of making wherein the filter media is secured to the filter support through the use of sintered metallic fibers of the same material type as the filter media and the filter support.
Another object of this invention is to provide an improved fluid filter assembly and method of making incorporating a sintered bonding pad of partially sintered metallic fibers for bonding the filter media to the filter support.
Another object of this invention is to provide an improved fluid filter assembly and method of making which enables a first and a second end of a cylindrical filter media to be bonded to a first and a second end cap in a single heating process.
Another object of this invention is to provide an improved fluid filter assembly and method of making which increases the surface area of filter media for increasing the capacity for collecting contaminants from the fluid.
Another object of this invention is to provide an improved fluid filter assembly and method of making incorporating a filter media which is bonded to a filter support through the use of a sintered fiber material and which eliminates the need for a braze material.
Another object of this invention is to provide an improved fluid filter assembly and method of making incorporating a filter media which is bonded to a filter support through the use of a sintered bonding fiber such as scrap filter media fibers.
Another object of this invention is to provide an improved fluid filter assembly and method of making which substantially lowers the cost of the filter assembly by eliminating the need for a braze material.
Another object of this invention is to provide an improved fluid filter assembly and method of making incorporating a filter media which is bonded to a filter support through the use of a sintered fiber material that is capable of withstanding a cleaning solvent and an elevated temperature.
Another object of this invention is to provide an improved fluid filter assembly and method of making having a filter media of uniform small diameter metallic fibers of less than 100 microns.
Another object of this invention is to provide an improved fluid filter assembly and method of making having a filter media of uniform small diameter metallic fibers formed through a wire drawing process to provide superior filtering capability for collecting contaminants from a fluid.
Another object of this invention is to provide an improved fluid filter assembly and method of making wherein the fluid filter insert is assembled with filter media to have superior sealing characteristics.
Another object of this invention is to provide an improved fluid filter assembly and method of making that is reliable for use over an extended period of time.
Another object of this invention is to provide an improved fluid filter assembly and method of making wherein a filter support is formed from a sintered assembly of metallic fibers.
Another object of this invention is to provide an improved fluid filter assembly and method of making wherein a filter media is bonded to a filter end member through the use of a sintered bond for bonding the filter media to the filter end member.
Another object of this invention is to provide an improved fluid filter assembly and method of making wherein a filter media which is directly bonded to a filter end member without the use of any additional bonding materials.
Another object of this invention is to provide an improved fluid filter assembly incorporating a filter end member which is formed from a sintered assembly of metallic fibers that replaces a conventional end cap of a filter insert.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as being merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention with in the scope of the invention. Accordingly other objects in a full understanding of the invention may be had by referring to the summary of the invention, the detailed description describing the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.